The present invention relates to a postage metering system that utilizes a digital printer and, more particularly, to a postage metering system wherein the postage metering system includes a meter vault and a replaceable digital printing unit which are physically separated.
Generally, a postage metering system includes a meter vault which accounts for the postage printed by a printing unit. The meter vault is comprised of a programmable microcontroller having a program memory for storing the system control program data. In an attempt to employ digital printer, such as, ink-jet, in the postage metering systems, it has been found that a print module configuration which includes the print heads, drivers and graphic imaging system within a single secure package is desirable. An electronic communication channel is provided between the meter vault and the print module to allow the communication of critical accounting and other data between the meter vault and the print module. This channel may also be used to allow communication between the print module and a mailing machine.
It is conventional practice to provide system software updates from time to time which either correct software defects, increase system efficiencies or add system functionality. Submitting the meter vault to system software updates or modifications has typically been accomplished in one of three ways. Under certain circumstances the meter vault must be taken out of service and returned to the manufacture where the security housing is removed and special equipment is used to load updated software into the program memories of the system. If sufficient unallocated program memory exists, it may be possible to connect a special service device to a communication port of the meter vault and down load the updated software into the program memory or other usable non-volatile memory. The service device must be specially equipped to preserve the security of the meter vault housing and internal circuit security of the meter vault. Another way is to trade out the existing meter vault with a new meter vault. All of these processes represent substantial time and cost consequences.
It is an objective of the present invention to provide a convenient means of up-dating the control program data for the meter vault and the mailing machine which overcome the time and cost consequences of the conventional processes.
A postage meter system in accordance with the present invention includes a base unit, more commonly referred to as a mailing machine, which serves as a platform for the meter unit. The base includes a microcontroller system which is responsible for controlling the transportation of envelopes in a sequential manner to a printing location whereat the printing unit can print a postage indicia and any other additional information, such as, an ad slogan, delivery address or bar code on the envelope. In a preferred configuration, it is contemplated that printing will accrue during relative motion between the envelope and the printing unit associated with the meter. Therefore, the microcontroller system in the base will be responsible for relatively precise control of the motion of the envelope through the printing location.
The metering is provided by way of two independent units which are a vault and a printer. The vault accounts for and dispenses funds for postal payment. Communication between the mailing machine, vault and printer is facilitated through a printer interface unit. The meter vault communicates with the print head to transfer encrypted messages for postage amount, piece count, and digital tokens. A digital token represents an alphanumeric sequence generated by using any suitable algorithm which uniquely identifies the postage indicia as originating from a particular postage meter system and verifying that that postage meter system is authorized for use by the Postal Authorities. Meter vault communications are routed to the print head through the printer interface. The meter vault securely communicates with the print head using any suitable digital encryption technique.
The printer interface serves as a junction board for the mailing machine, meter vault, slogan box, and print head. This minimizes the number of connection points in the system. The printer interface provides the connections for a serial communication linkage and unregulated DC power from the mailing machine to the meter vault, transfers print command and status signals between the mailing machine and print head, interfaces the slogan box to the print head, supports a unique serial link between the meter vault and print head, and regulates logic and print nozzle power from the mailing machine to the print head.
The slogan box stores graphics images representing the fixed part of the standard indicia (e.g., the eagle printed on US mail), low-value indicia, permit mail indicia, town circle (where appropriate), inscriptions, and customer slogans. It also stores the fonts for printing the variable data on the mail piece. All of the graphics data is either encrypted or signed, that is, subject to other types of encoding algorithms in the slogan box non-volatile memory. The encryption or signing is done at the manufacture""s facility. Only the print head contains the necessary decryption key to properly interpret the data.
The communication by the meter vault includes encrypted information. Only the meter vault and the print head know the proper keys to utilize the information. The keys are stored in an ASIC on the print head to reduce the opportunity for fraud. The microcontroller on the print head controls the printing operation including loading of NVM, decoding of messages with assistance of a DES engine on the print head ASIC, and initiating of printing. The microcontroller helps to reduce the complexity of the ASIC.
The print head ASIC decodes the mail position for printer sequencing, provides the proper timing for driving the print nozzles, supports external ink supply monitoring, interfaces to the NVM; support external communications, and performs self-test functions. The print head NVM also stores inscription representations. The meter vault stores a table of enabled inscriptions. When the operator at the mailing machine wishes to select an inscription, the print head transfers a list of the available options to the meter vault. The vault screens for only the enabled inscriptions and sends the information to the mailing machine. The operator""s response is forwarded from the meter vault to the print head.
As part of the system start-up process, the print head issues a message to the meter vault which directs the meter vault microcontroller to receive updated program data, only if, that updated program data version has not already been written to the non-volatile memory of the meter vault. The print head then encrypts the updated program data and transmits that encrypted data to the meter vault. The microcontroller of the meter vault then decrypts the updated program data and stores the data in the non-volatile memory of the meter vault. The program update code is loaded into the print module after fabrication by the manufacture and prior to shipment.